The invention relates generally to traveling water screens and, more particularly, to water screens that travel in a generally horizontal direction across a flowing stream of water.
Water is diverted from rivers, lakes, and other bodies of water for municipal, irrigation, and industrial purposes. Fish or water screens serve as filters to prevent fish or debris from entering a water diversion. These screens range in size from a few square feet to several thousand and come in many shapes.
Rotary drum screens consist of a screen mesh wrapped around a cylinder rotating on a generally horizontal axis. The top of the cylindrical screen is above the surface of the water. Debris is carried over the screen as it rotates and is washed off on the downstream side. Because of their fixed diameters, rotary drum screens are restricted in how deep they can be submerged and do not accommodate varying water levels. If the water level is too high, fish and debris are carried over the top of the rotary drum. If the water level drops too low, the screen clogs and water flow is restricted.
Fixed plate screens are also widely used. These stationary plate screens consist of fixed perforated metal sheets or wedge wire panels, usually oriented vertically in a flowing stream of water. Although the fixed plate screens are themselves simple, they require an external cleaning system to prevent clogging. External cleaning systems for plate screens are high maintenance and often not effective. And, if the cleaning system fails, the clogged screen can collapse. External brush cleaners, which are often used, can injure or kill fish.
Another kind of frequently used screen is a vertical traveling screen, which consists of a vertically advancing mesh driven by rotating shaft-mounted sprockets. The axes of the shafts are oriented generally horizontally. The screen may be inclined in the direction of water flow to aid in debris removal. To screen wide diversions, several side-by-side vertical traveling screens have to be used because individual wide vertical traveling screens are expensive to build, support, and drive.
Thus, there is a need for a water screen that is easy to clean and useful in filtering debris from wide diversions.